4. Broil or grill burgers for 5 to 7 minutes on each side until browned, turning once. Remove burgers from heat and allow to rest for 2 minutes.

5. Warm the pita breads in a pan or on a grill; make a slit on the side of each pita. Place some of the lettuce and sliced onion in each pita, then place a burger inside each one. Spread with yogurt or Tzatziki and season with salt and pepper to taste.